If a picture doesn't load automatically, right click on
it and left click on "show picture".

I am compelled to add a few words of caution and disclaimer
to this brief explanation. Remember that the manufacture of
black powders is a regulated activity in many areas. One
should do some research into the legal requirements before
attempting to do any of these steps. The procedures
described represent my own experience and are not
necessarily recommended as the final word in how to do it
properly and safely. These explanations are made available
to others in order to stimulate constructive dialog for
enhancement or improvement.

Without black powder in all its varieties, it would be
tough to make much more than sparklers for pyrotechnical
displays. Making high performing black powder is one of
the fundamental skills that the aspiring pyrotechnician
will probably want to master early in his quest for
knowledge in the field. The goal of this meager treatise
is to illustrate the most popular method of amateur
production which is called the "ball milling method."
This implies that anyone who wants to use this approach
will need to first build or have access to an efficient
ball mill . Without a mill, one
is left with the inferior alternatives of using the CIA
(precipitation) method or the incredibly laborious
mortar and pestle method.

The first step in the process is to assemble the raw
materials. In this case, there are only three, as
pictured: potassium nitrate, charcoal and sulfur. Of
these three, potassium nitrate and sulfur can readily be
purchased from pyro supply companies such as
Skylighter
or AMERICAN
PYROTECHNIC SUPPLY, but charcoal is a different story. The
subject of charcoal could require a whole book to
adequately cover. For the purpose of brevity, this text
will assume that willow charcoal is one of the most
popular choices for making high performance black
powder. Unfortunately, commercial sources (at least in
the US) for this particular kind of charcoal are very
rare. The best approach is to make it yourself with a
home-made charcoal cooker.
Then you can control some of the characteristics of your
charcoal by custom cooking it to your liking. .

If you make your own charcoal, you need to reduce it
from the original sticks to a more usable powder form. I
use the meat grinder method shown here. A guide chute
has been fashioned from a sheet of transparency film to
help keep the dust down. This is definitely not a job to
do in your kitchen unless you want to risk sleeping in
the garage for a month. A good respirator is also
recommended. The result is a charcoal powder which
ranges from air float to about -8 mesh. This may or may
not be useful "as is" for making black powder, depending
upon the approach used to make the green meal.
Hopefully, this will become clear in a moment.

Regardless of the method used to make the green meal,
the proper proportions can only be achieved by weighing
them on a scale. I generally use the traditional ratio
of 75 parts potassium nitrate, 15 parts charcoal and 10
parts sulfur. If your black powder is intended primarily
for use as lift powder, you might want to use the ratio
which is purported to be optimized for this purpose. It
is 74 parts potassium nitrate, 14 parts charcoal and 12
parts sulfur. Just remember that these are parts by
weight. It seems that every "newbie" to pyrotechnics
will reveal his ignorance by asking the question
concerning whether parts in a formula refers to weight
or volume. Save yourself the embarrassment and etch upon
your mind that pyro formulas are always in parts by
weight unless specifically stated otherwise. The
triple-beam balance scale shown does the trick quite
nicely for weighing out parts of a formulation, but you
can accomplish the same purpose with a much less
expensive home-made scale .

Let's diverge to a little background discussion for a
minute. The green meal referenced above is the raw,
unprocessed mixture of the constituent ingredients.
There are two basic approaches to creating this initial
mixture. One method is to create a bulk mixture from
which a "volume measured" portion is taken and placed in
the milling jar. The other approach is to create a batch
of green mix which is exactly the amount needed for the
intended milling jar charge. In the first case, the
particle size of the individual components of the mix
must be small enough to assure homogeneity. In the
second case, there is no concern about the green meal
being homogeneous. The potassium nitrate and sulfur can
be full of lumps and the charcoal can be very coarse.
The proper weight portions are just loaded into the mill
jar and the milling accomplishes the homogeneity. The
second approach has many advantages, but it can only be
done if the user knows the exact weight of the optimum
charge for his milling jar. For the purposes of this
discussion, the definition of an optimum charge is the
following: the amount of fully milled black powder meal
which occupies 25% of the mill jar volume. The
determination of this optimum charge is challenging
because milling will often alter the volume of that
which is milled. The best way to determine the weight of
the optimum charge is to actually weigh the desired
volume of finished meal. This implies that the user of a
new milling jar must
use the first approach to making green meal for his
first batch. The optimum charge is then determined and
can be used for all succeeding batches.

The first approach to making green meal will be
demonstrated because it also includes many principles of
properly mixing pyrotechnic chemicals. In general,
successful pyrotechnic compositions work well because
their proportions of ingredients have been very
carefully determined. If the pyro-technician allows the
proportions of his mixture to vary from the ideal, the
performance of the composition will usually suffer.
Therefore, except in a few unusual cases, a high degree
of homogeneity is desired in pyrotechnic mixes. One of
the best ways to accomplish this is by using screening
(which requires a good set of
mixing screens ) as a means of mixing pyro chemicals
together. In the picture at the left, is shown the
results of screening a mixture of the potassium nitrate
and sulfur which were weighed out for the bulk black
powder green mix. The two chemicals were stirred
together and appeared well mixed. However, upon passing
the mixture through a 40 mesh screen, many large lumps
of sulfur are revealed. These lumps obviously destroy
the homogeneity of the mix in their near vicinity.

In order to eliminate these lumps, I perform a rough
approximation to a mortar and pestle operation by
placing the lumps in a container. The lumps are crushed
by the back of a spoon against the sides of the
container. The contents of the container are then
returned to the mixing screen box and the cycle is
repeated until all of the material passes through the
screen. The entire quantity of mix is then passed
through the screen several more times to ensure a
thorough mixture. This method works well if the lumps
aren't hard and dense. If they are too hard to crush
easily, the best way to eliminate them is by milling
each chemical separately prior to mixing with others.
Now, to complete the black powder green mix, the
charcoal must be added. The screening method could have
been used to mix all three chemicals together in one
step, but I prefer to add the charcoal as an "airfloat"
which will be free of coarse particles. The charcoal is
added to a container with the screened potassium nitrate
and sulfur, a tight lid is used to close the container
and the container is shaken vigorously. I do this
because screening any mix which contains fine charcoal
will usually result in a lot of airborne dust which
enters the lungs and coats the pyro lab with a nasty
black film. At this point, a black powder green meal
with a reasonable degree of homogeneity has been
achieved.

Now a volume of green meal equal to 25% of the mill jar
volume is measured. For this jar, that volume is 3 and
1/4 cups of our bulk green meal. This is the first
approximation to the theoretically ideal mill jar
charge. It is added to the jar along with hardened lead
milling media equal to 1/2 of the mill jar volume. In my
experience, the volume of the black powder meal will
increase during the milling. If you have a high
efficiency mill, the milling process will be complete in
about 3 hours of milling time. I would be remiss if I
didn't mention that the milling should be done with all
the due precautions taken. This means locating the mill
remotely and perhaps using protective barriers around
it.

The powder which results from the milling process is
still referred to as "meal" because it is not yet very
useful for pyrotechnic applications. However, it is no
longer called green meal. The meal is processed into
grains of black powder by a method known as corning. The
size and characteristics of these grains will determine
some of the aspects of the performance of the finished
black powder. The first step in the corning procedure is
accomplished by using a powder die
to compress the milled powder into "press cake". One
of the secrets of making durable black powder grains is
to add sufficient moisture to the meal prior to pressing
it into the cake. I add 4 grams of 50% water/50% alcohol
to 119 grams of milled meal to make an individual die
batch. This is done by placing the meal and
water/alcohol in a mixing cup and stirring vigorously
with a stirring rod. The milled powder will undergo a
fairly rapid transition from fluffy, loose powder to a
stiff, but still crumbly powder when the moisture
becomes well distributed. Some will advocate adding
moisture by misting it lightly onto a pile of milled
powder while mixing with the diapering method.
Theoretically, this avoids degrading the performance of
the powder by not giving the potassium nitrate a chance
to dissolve and recrystallize. However, I have found
this trouble to be unnecessary. The picture shows the
dampened, milled powder being added to the powder die,
after which the compression piston is placed on top.

Next, the die is placed in a
home-made hydraulic press and the press is operated
from behind the blast shield. This picture is
illustrative of the pressing step, but in actual
operation I recommend the use of a heavy glove on the
hand which is used to pump the hydraulic jack. This and
a heavy sleeved shirt or coat are a good idea. The die
has been designed so that the finished press cake has
the desired density of 1.7 grams/cc.

These are the puck shaped pieces of press cake which are
extracted from the powder die after pressing has been
completed. They are rock hard and should hold together
well without crumbling. If the press cake crumbles
easily, this is one indication that insufficient
moisture was added to the milled powder. The press cake
pucks are allowed to air dry for at least 24 hours
before they are crushed into powder grains. Tapping on
the pucks with a wooden dowel makes a china-like
clinking noise even right from the powder die. After
drying for a day or so, the pucks will ring even a
little more, indicating that the moisture level is about
right for the final step of the corning procedure.

Crushing the press cake into useful grains is somewhat
nerve-wracking for me, but I like this step because it
is the last in a long series required to finally obtain
high performance black powder. I use a small baseball
bat to crush about 1/2 of a press cake puck at a time.
The chunk of press cake is placed in an old aluminum
pressure cooker pan and the bat is used in short,
downward strokes to break up the cake. This works best
if the pan is placed on a very hard surface, such as
concrete or stone. The idea is to fracture the cake into
grains without crushing it back into useless powder.
Again, for safety's sake, this should be done outdoors
with protective clothing and always avoid placing your
face directly over the pan. If 60 grams of black powder
were to ignite in the pan, it would create a hot flame
as much as 4 feet high before your reaction time would
allow you to get out of the way. As I said, this step is
a little nerve-wracking, but I have never had an
accident during this step yet. There may be some
arguments for using a plastic bucket instead of an
aluminum pan, but I'll leave this choice open to
discussion.

The contents of the crushing pan are emptied into a
stack of screens to separate the various desired grain
sizes. Whatever will not pass through the top screen is
returned to the pan for more crushing with the "bat
pestle" and this cycle is repeated until all the black
powder cake passes through the first screen. A little
side to side shaking of the screen stack during each
cycle helps the grains settle to their proper location
in the stack. This particular stack of screen boxes
consists of the catch box, a 40 mesh, a 20 mesh, a 10
mesh and a 4 mesh screen on top. The powder which falls
clear to the catch pan is a -40 mesh powder which is
retained for use whenever meal D is called for in my
pyro formulas. The powder in the 40 mesh box is a 20 to
40 mesh powder which is used as 4FA equivalent. The
powder in the 20 mesh box is a 10 to 20 mesh powder
which is used as 3FA equivalent. Finally, the powder in
the 10 mesh box is a 4 to 10 mesh powder which is used
as 2FA equivalent.

This picture is shown to give an idea of the various
grain sizes relative to common US coins. Now I'd like to
explain a little about my philosophy regarding my choice
of screens for separating the grains into these ranges.
The ranges don't conform exactly to those given for the
common commercially produced powders and this is
intentional. The only motivation I can think of to
conform more closely with the commercial definitions for
black powders is to enable a completely transparent
exchange of commercial and home-made powders in
pyrotechnic projects. In these cases, the pyro craftsman
wants his home-manufactured powders to perform
identically to commercial powders so that he can always
expect consistent end results. In my case, I don't use
commercial powders. Therefore, I can afford the luxury
of adjusting the amounts of powders used in my projects
according to the desired results. This way, my only
concern is to make my own manufacturing process very
consistent so that my home-made powders always give me
the same results. The advantage of this approach is that
the ranges of grain sizes for my equivalent powders
don't overlap as they do in the commercial ranges. This
means that I can use commonly available screens and do
multiple separations in one step as illustrated above.

I
approached this project the patient way and started by
first ordering the milling bible entitled "Ball Milling
Theory and Practice for the Amateur Pyrotechnician" by
Lloyd Sponenburgh. I have not faithfully followed his
plan, nor do I expect you will follow mine. However, for
those of you who are dying to build your mill without
buying the book, this page illustrates the general
approach.

I have pictured
the entire mill here for visual reference as you look at
the remaining illustrations.

First, you have to
decide what kind of frame to mount your mill on. I
simply made a rectangle with 2 X 4's and screwed two
layers of 1/2 inch plywood on top. Whatever you
use, it must be very sturdy!! These mills must endure
heavy vibration and weight loads.

The electric motor
should be a 1/3 to 1/2 horsepower, capacitor-start, 1725
rpm, 115v motor. You can get one from Grainger using
part # 6K758. In my case, I am using a motor salvaged
from a washing machine for which I paid $10. Since it
has coils for 2 speeds, I used 2 switches. One switches
between hi and low speed and the other is the on/off
switch. It turned out that I only use the fast speed, so
the speed switch is superfluous. The shaft sheave on the
motor should be 2 inch o.d. by 1/2 inch (Grainger
#3X895).

The drive shaft
for the mill is 5/8 inch round steel bar stock. These
can be purchased at any hardware store. Be sure it is
perfectly straight. The sheave on the drive shaft is a 6
inch o.d. by 5/8 inch (Grainger #3X919). This cost me
$3.72. You will also need two self-centering
ball-bearing pillow-block bearings to mount the drive
shaft (Grainger #2X898). I had to sand the drive shaft a
little bit to allow the bearings to slide onto the
shaft.

Before placing the
bearings on the shaft, you need to place a piece of
automotive heater hose on it as shown here. This hose is
5/8 inch i.d. by 7/8 inch o.d. It can be found at most
hardware or auto parts stores. A little lubrication of
some kind on the shaft will greatly aid the sliding on
of the hose.

The other side of
the mill jar cradle uses a ball bearing equipment
roller. I bought this one at Woodworker's Warehouse for
about $10. This picture shows the roller removed from
its bracket. The roller has been covered with two layers
of bicycle tire inner tube. The inner tube layers have
been folded back in the picture for illustrative
purposes only. You may be wondering how to get the inner
tube layers over the roller. Again, Lloyd describes a
technique which works very nicely.

Start with a 26 inch by 2 inch bicycle tire inner tube.
Cut the deflated tube about 3 inches from the valve stem
and tightly tie a cord around each end so the tube can
be inflated to look like a long three inch diameter
sausage. The trick is to push the roller end into the
end of the inflated inner tube. When the roller is
completely enclosed by the inner tube with a few inches
of overlap, you can cut the sausage off near the valve
stem to allow it to deflate. You now have two layers of
rubber over the roller which are connected at one end.
After allowing the rubber to relax a little bit, you can
now trim the ends with scissors to within 1/4 inch of
the ends of the roller. Now re-install the roller in its
bracket and check for unimpeded rotation.

If you mount the
drive shaft and equipment roller perfectly parallel,
your mill jar may not creep as it rolls in the cradle.
To be safe, I installed this bumper to prevent the mill
jar from exiting its cradle. I used two Teflon furniture
slides on the bumper to allow the mill jar to slide
against the bumper with little friction. The drive shaft
and equipment roller are mounted with 3 inches of space
between them to accommodate both a 4 inch and 5 inch
mill jar. A 6 inch mill jar requires a space of 4.5
inches.

This is a mill jar
which has been constructed from 5 inch PVC pipe and
fittings. The milling media is antimony hardened, 3/4
inch lead balls. The construction of the jars is
relatively simple, but is a subject for another project
page.

Finally, this shot
shows the placement of the 5 inch mill jar in the
cradle. With this setup, I can mill about 3 1/4 cups of
high quality black powder in about 3 hours. The
efficiency of this mill is dependent upon many factors
which are explained in Lloyd's book. There is a wealth
of information about milling theory contained in the
book and I would highly recommend the serious
pyrotechnician to purchase it. You can find it in the
books and
video section of Skylighter's web catalog.

There are as many ways to produce charcoal as there are
pyro enthusiasts. There are certainly many approaches
that are simpler than my method. I will try to point out
the advantages of this particular charcoal cooker and
leave it to your judgment to determine whether it has
merit. As always, I invite critical commentary, but
praise and homage is preferred.

This is a typical
22.5 quart or 6 jar canner pot. It is used to can fruits
and various garden grown produce. The pot is constructed
of fairly light weight sheet metal which has a tough
porcelain finish. It comes with a wire basket which
holds the canning jars securely inside during the
canning process. You can purchase one of these at
Wal-Mart type stores for about $14.00. This is used as
the "oven" part of the charcoal maker. There are many
alternatives to using this particular kind of pot.
Various metal drums or metal buckets will work just as
well.

A lid for your
"oven" must be fashioned with a hole in it where the hot
gases can exit. The idea is to create a draft of hot
gases from the bottom of the oven to the top. If you use
this kind of pot, it's a good idea to cut the hole with
minimal damage to the surrounding porcelain.

Next, the holes in
the bottom of the pot are made. I placed a length of 3
inch paper mortar tube with its face against the inside
bottom of the pot, beneath the site of each hole. This
gives firm support to the bottom surface which avoids
cracking the porcelain while the holes are formed. A
sharp blow with a hammer on a center punch creates a
hole about 5/16 inch in diameter. I created 30 holes in
an evenly distributed pattern on the entire bottom of
the pot.

Now, the theory is that the oven temperature could be
regulated by the number of holes in the bottom. More
holes allow more draft and consequently a hotter fire. I
tried to create the holes in groups that would
accommodate the addition of rotating hole covers. This
should achieve the desired temperature regulation, but I
have yet to experiment with this concept. Currently, the
30 holes result in an oven temperature of about 575
degrees F. Another enhancement would be the addition of
standoff feet on the bottom of the cooker. I just set
the pot on 3 rocks during operation.

Now we turn our
attention to the retort container. This pot is a
miniature version of the oven pot. I bought it at a
garage sale for $1.00. Wood stove cement and fiberglass
gasket material were used to seal the lid which is held
in place by 4 mini C-clamps. A single 5/16 inch hole was
punched in the lid to vent the smoke from the retort. I
like this retort can because it will last for dozens of
uses before it will need to be replaced. The handle is
handy for lifting it in an out of the oven with a wire
hook.

Many simpler
alternatives can be considered for the retort container.
These Christmas cookie cans work great. Add a couple of
screws to hold on the lid, put a hole in the top or
bottom and you're all set. (Editorial comment: You know
you're a pyro when you buy stuff you don't need just to
get the container. I don't care for these cookies, but I
will gag them down just to justify buying the can.) My
objection with this approach is that this kind of
container will only last for about 5 or 6 roastings
before the thin metal walls loose their integrity. Then
I have to eat more cookies.

If you really want
to become a gourmet charcoal cooker, you might want to
consider buying one of these flu thermometers. This one
cost $11.00 and was purchased at a hardware store that
carries wood stove products. It is magnetic and will
stay anywhere you put it on the retort if the retort is
made of iron. Perhaps you are asking....Why do I care
what the temperature is in my oven?

Let's slip into the theoretical domain again for a
moment. Charcoal made at lower temperatures contains a
higher percentage of volatiles in it. This leads to
black powder that ignites easier, which would be
desirable for black powder based primes. Charcoal made
at higher temperatures contains less volatiles, ignites
at higher temperatures and may be more desirable for
creating lift and break powders. I don't know if there
is a strong consensus among the pyro community for these
theories. At any rate, the addition of the above
temperature gage to your retort gives the appearance to
the uninitiated that charcoal making is nearly as
complicated as rocket science.

OK, we've finished
making our primo charcoal cooker. Let's talk about how
to use this hi tech apparatus. Perhaps the most labor
intensive part of making charcoal is the preparation of
the wood. When using willow, you must remove the bark
and split the sticks into smaller sticks no thicker than
1/2 inch. I load the retort as full as possible with the
sticks oriented vertically.

Now we need a fire
in the oven. I use two layers of regular barbecue
briquettes to fuel the fire. I place the briquettes in
the bottom of the pot with the wire basket in place. The
handles of the wire basket are removed so they don't
interfere with the placement of the retort. This keeps
the retort from settling and choking off the intake
holes at the bottom of the pot. My kids think it's
pretty funny that I use charcoal to make more charcoal.
I'm afraid they tell their friends, "He's a nice guy,
but sometimes he ain't too bright!" This picture shows
the cooker in operation. The flu temperature gauge is
placed so it is visible from the hole in the lid. A nice
column of smoke is rising from the retort vent and the
smell of smoky campfire fills the air (and sometimes my
house when the wind is right.)

A
close examination of the smoke column reveals an
interesting fact about the operation of this cooker. The
smoke is not visible until the gas jet rises several
inches above the retort vent. This implies that the
escaping volatiles don't condense into visible smoke
until they cool in the rising column. This is the main
advantage of this kind of charcoal cooker. Allow me to
explain...

In
my days as an apprentice charcoal maker, I would simply
place the retort can over an open fire. I found that it
was difficult to achieve a steady, well controlled heat
source. I had to constantly add fuel to the fire and
check it often. Even with great attention, the heat was
not distributed evenly. The result was that there were
often cool spots in the retort where the charcoal was
brown instead of black, indicating that the wood
conversion to charcoal was not complete. Even worse,
cooler areas of the retort lid would allow condensation
of the reaction gases on the inside of the lid. The
accumulation of these tars left a mess that was
impossible to remove. All of these problems are
eliminated by the new cooker. Now, the retort stays
fairly clean, I don't have to constantly tend the fire
and the temperature is even and controllable.

Finally, the
result of all this effort is beautiful, almost shiny
black charcoal. Getting it into usable form is another
story. I use a meat grinder for the first stage of
reducing it to useful grain sizes. It was suggested in
the April 98 AFN that you use gallon size zip lock bags,
remove excess air and whack and roll it with a PVC pipe.
The resulting charcoal powder is then graded with
various screens. For airfloat, of course, you will need
a ball mill. Whatever your method, you will get pretty
grubby and will probably blow black stuff in your
Kleenex for a week.

If you want to get into amateur pyrotechnics, a scale is
essential. A commercial triple-beam balance scale can
cost $85 to $100. Electronic scales will cost you at
least as much. If this kind of expense is a big obstacle
to your pyro ambitions, then you might be interested in
this low cost plan to build a balance scale.

The heart of a
balance scale is the balance beam. This plan uses a
piece of hobby poplar, 1/2" X 1 1/2" X 16". You make a
low resistance fulcrum with two sheet rock screws which
protrude slightly from the beam to form the bearing
points.

Some careful
precision is needed to ensure that the screws are placed
on a line which is perpendicular to the line of the
beam. I used a T-square to draw the line and a drill
press to drill guide holes for the screws.

The ends of the
beam are constructed as shown to lower the swivel point
of the weight pans. This is done by simply gluing
another block of poplar to the bottom of the beam at
each end. Next, the hooks are added from which the
weight pans are hung. Finally, pieces of threaded rod
are screwed into the ends of the beam and 2 or 3 nuts
are screwed onto the rods. These are used as adjustment
weights to cancel any asymmetries in the balance beam.

A pointer stick
may be added to make it easier to detect when balance
has been achieved while measuring chemicals. I used a
left over piece of a model rocket kit and sharpened one
end for the pointer. This is simply glued on with help
of a square for alignment.

Weight pans can be
suspended from the beam ends in many different ways. My
first method used 2 loops of nylon kite string threaded
through a square piece of fiber board bathroom paneling.
A later improved method used coat hanger wire to support
the weight pans.

The final part of
the project involves constructing some kind of a stand
for the fulcrum bearing surface. This can be
accomplished with a simple vertical piece of wood which
has a small metal plate mounted on top. A shallow groove
is scored in the plate and the sheet rock screw points
of the balance beam are placed into the groove. I used a
surplus microscope stand for my scale. I then made
weights from pieces of plumber's solder which were
weighed on a high precision electronic scale and trimmed
to the desired weights. The final result is a scale
which is highly accurate and incredibly cheap to make.

As with most home-made tooling, there are many ways to
make milling jars. I have yet to see a design I like
better than this one which uses PVC pipe and fittings.
The jars are very sturdy and will last for many years.
Their initial description was supplied by Lloyd
Sponenburgh.

The quart size jar
uses 4 inch PVC and fittings. It is the smallest and
cheapest jar to construct. However, its milling capacity
is so small that it is only useful for small batch,
specialty milling. This is the parts list: a 4 inch end
cap, a 5 inch length of 4 inch I.D. schedule 40 PVC
pipe, a 4 inch to 3 inch reducer, a short stub length of
3 inch I.D. PVC and a rubber test cap with band clamp.

The above parts
are all glued together with PVC glue to yield this
result. As you can see, the jar with the flat end cap is
nice because it will stand up by itself. If you use a
rounded end cap, I recommend putting 3 rubber feet on
the bottom of the end cap to stabilize it. The rounded
end cap also results in a larger capacity jar. The
actual total capacity of the flat bottomed jar is about
1 quart plus 1/2 cup. It will require a volume of 1 pint
plus 1/4 cup of milling media and will yield a charge of
1 and 1/8 cups of milled powder. This illustrates the
Sponenburgh rule of thumb for milling jar capacity which
is: Fill your jar half full of milling media to mill a
charge of 1/4 of the jar volume.

The 5 inch jar is
about right for most of my milling jobs. The same parts
as above are needed, but in the 5 inch sizes. There are
a few quirks, however. The supplier in my area does not
carry a simple 5 inch to 3 inch reducer. The reducer
shown fits inside the 5 inch coupler. This requires the
addition of the coupler to the above parts list. The
other complication is that there are lots of ridges and
raised lettering on the outside of the coupler that have
to be removed to achieve a smooth outer surface on the
jar.

Shown here is the
rounded end cap, a 6 inch length of 5 inch I.D. PVC and
the coupler with the raised ridges removed. A radial arm
saw was used to remove the ridges, but a belt sander
would probably work better.

When these three
parts are glued together, the 6 inch length of pipe
becomes entirely enclosed by the coupler and endcap
because the distance of insertion into each one is 3
inches.

The reducer is
prepared by clipping off the corners which otherwise
would protrude beyond the outer surface of the jar. A
short length of 3 inch PVC is cut so that 3/4 inches
will protrude for the attachment of the rubber test cap
lid. Note that the lid in the next picture has been
trimmed back to a width of 3/4 inches to make it much
easier to attach and remove.

The final volume
of this jar is 3 1/4 quarts and the charge capacity is 3
1/4 cups. Again, the addition of stick-on rubber feet to
the bottom of the rounded end cap is recommended. A few
final notes: Mill jars, like screens should be reserved
for certain classes of milling. I have separate jars for
milling black powder, oxidizers, (chlorates get their
very own jars) benzoates and binders. Care should be
taken with your milling media, as well, to avoid cross
contamination. I use ceramic media to mill most single
substances. Lead media is used to mill black powders,
rocket fuels and charcoal. This same approach can be
used to make milling jars of 1 gallon capacity by using
6 inch PVC pipe and fittings. The drawback is that a jar
of this size will require 30 pounds of lead milling
media. That represents a big pain in my back to lug
around and in my wallet to purchase the media.

I couldn't find the rubber end caps in my area, but the 3"
ABS test caps fit right on the outside diameter of the 4" to
3" adapter tightly, no clamp required.

I have read information indicating that PVC will not show
on X-Ray. This requires exploratory surgery to locate
fragments in the human body as PVC will cause severe
infection if not removed. To solve the problem I
purchased a six inch HDPE mortar, cut it into 14 inch
lengths and purchased six inch pipe plugs to close the ends.
The plug is called "Gripper" and is manufactured by Cherne
Industries, Inc. They come in various diameters. I purchased
the 6 inch plug at Schimberg Co., a plumbing supply company,
here in Cedar Rapids, Iowa for $16.91. These are kind of
costly, but these jars are very easy to clean and if
detonation were to occur there would be no risk of shrapnel.

I have a tip on stabilizing ball milling jars. Instead of
applying rubber sticky feet to the jars, just cut an inch or
so tall cylinder of the same pipe used in the jar and glue
this to the convex bottom of the endcap. This results in a
very stable base that is accurate and also very durable.

Conventional wood framed screen boxes are usually about
1 ft. square and 3 or 4 inches deep. I find this much
screen area to be more than is necessary. Cleaning them
is difficult because of all the corners. Stacking them
for multiple grain separations is awkward unless extra
rails are added around the tops of the frames. Then you
have more corners to clean. All these problems can be
solved by using plastic storage containers as frames.

This is a typical
shoe box size plastic storage container. They have very
smooth, water-proof surfaces and rounded corners for
easy cleaning. They should have stop tabs on the
exterior which allow you to stack one inside another
with about an inch of clearance between the bottom
surfaces. They seal fairly well when stacked to control
dust nicely.

First, get a sharp
utility knife and cut out the bottom of the container,
leaving about 1/4 to 1/2 inch of a lip around the edges.
Usually the container will have a raised ledge molded
into the bottom which makes a good guide for cutting.

Now cut your
screens to size so that the screen is larger than the
hole in the bottom of the container. You should be able
to get 2 screens from a square foot of screen cloth. Two
for the price of one!! Now, you will need some good tape
(duct or strong masking tape) and some good quality
epoxy glue.

Before applying
the epoxy, you should rough up the gluing surface of the
plastic with some coarse sand paper.

Then mix up the
epoxy, apply along one edge, put the screen in place and
apply the tape over the screen where the epoxy is. The
tape should hold the screen tightly against the
container frame while the epoxy sets. Now repeat the
procedure for the remaining three sides. If you have a
well behaved screen that lies nice and flat, you might
be able to get away without using epoxy at all and only
use the tape. This is much less trouble, but also much
less durable as you can imagine.

Voila!! The
finished result is a compact, stackable, light weight
set of screens with a convenient catch box which is
merely another unmodified container. I'm so pleased with
them that I seldom ever use my original, wooden box
screens any more.

Your screen idea is neat. Mine are nearly the same, except:
a. I put my screens on the inside.
b. I fasten them down with automotive "blue goo" so they are
very easy to take off and replace.

This powder die design was invented by Lloyd Sponenburgh.
In fact, this die was even made by Lloyd because I
bought it from him when he was still in the business of
selling BP making tools. Unfortunately, Lloyd no longer
sells this useful item, but you can fairly easily make
your own. He has, however, described how he makes them
in the pyro news group. I assume he won't mind if I do
the same on this web page.

This is the base
of the powder die. It consists of a five inch length of
3 inch I.D. PVC and a base cylinder of cast resin. The
cylinder looks a little blotchy because of black powder
stain and is quite heavy because of its length. The only
utility of this exaggerated length is the avoidance of
excessive blocking if you use a press with high
clearance. A much shorter, lighter base would still work
just fine. Notice that the PVC sleeve is held fixed,
relative to the base cylinder, by a set screw. The
function of this sleeve is to position the cylinder a
defined distance into the compression sleeves pictured
below.

The compression
sleeves are made from a 3 inch length of 3 inch I.D. PVC
and a "repair sleeve". The repair sleeve is similar to a
coupler, except it has no stop ridge in the center. Both
of these sleeves have been split by cutting with a very
narrow kerf blade down the length of the sleeve. In use,
one sleeve fits inside the other, with the splits
opposite each other, and they are restrained from
expansion by two common pipe clamps.

When placed on the
base, the compression sleeves form the walls of the
chamber where black powder meal is placed to be pressed.

The top piston is
another cylinder, similar to the base cylinder, which
has been made from a casting of resin. Read the feedback
at the bottom of the page from Lloyd to find out about
how to make these castings.

The top piston is
placed into the compression sleeves after the black
powder meal and pressed until a known density has been
achieved. On this top piston, a groove has been placed
to indicate that when it is even with the top of the
compression sleeves, 8 ounces of meal will be at the
desired density of 1.7 grams per cubic centimeter.
Likewise, 4 ounces of meal are pressed until the top of
the piston is flush with the top of the sleeves. The
press cake that results from this pressing process will
be very hard and sounds like china when tapped. After
corning, you will have a very durable, hard grained
powder.

I'll gladly supply the composite formula for you, but when
you hear it, you'll DIE of laughter.

I wanted something that would both lower the cost of the
resin casting and provide a strong matrix. Chopped fibers
were out for cost, and organic fillers for lack of strength.
I settled on 'sharp sand'. No kidding!! It's called sharp
sand in some circles, mason's sand in others. Sack Crete
Corp. puts it up as 'fine blasting sand'. River sand is
smooth, and makes a weak matrix. Add sand to mixed polyester
resin (fiberglass resin) until it makes a very thick but
still pourable batter. If I recall (without my docs book in
hand) about 24 fl.oz. of resin to one quart dry measure of
sand works out about right. I cut back to about 60% of the
recommended hardener, because the large castings get very
hot, and will crack as they cure if you add too much
hardener. You want enough sand so that no resin 'settles
out' to the top after you fill your forms. The ratio is
fairly critical, but quite easy to discern. If liquid resin
rises to the top after pouring, you need more sand next
time. DO make sure your moulds are accurate. You'll never
cut this stuff after it's cured. The silica makes ALL metal
tools go bye-bye on the first contact. I had to mill the
calibration grooves in my pistons with a solid carbide bit,
and that had to be sharpened every two or three cuts.

I mix Vaseline with toluene as a mould release, and simply
paint on a VERY thin layer with a soft bristle brush. The
Vaseline will melt with the heat of the casting, so go
sparingly, or you'll have a puddle of grease on your resin
as it cures. My moulds were cleaned-up pieces of PVC DWV
pipe clamped to a foil-covered piece of aluminum plate. The
resin shrinks slightly on cure, and the castings just
slipped out without any difficulty. But if a casting stuck,
I could unclamp the pipe from the base plate, and push the
casting out from one end.

Lloyd

Due to several requests for exact dimensions, I have added
the discussion below to clarify the design of the powder
die.

The top piston ram is 5.36cm high.
The 8 oz. mark is 1.46 cm below the top.
The base cylinder enters the compression sleeves by 0.8cm.

Now for the math just to verify the theory.

The compression sleeves are 3 in. or 7.62cm long.
Subtracting the size of the top ram and base intrusion:
7.62 - 5.36 - 0.8 = 1.46 cm for a 4 oz. BP cake
and 2.92 cm for an 8 oz. cake. These are the cylinder
lengths (L) for each cake.

The volume of a cylinder is (PI * (D/2)**2) * L where
D is the diameter and L is the length.
For the 8 oz. cake this becomes 3.14 * 14.516 * 2.92 =
133.16 cc.

I finished the BP Die design program this morning. I have
written this program for you and all who wish to use it. If
you feel this program worthy I will leave this link for all
to download or feel free to add the program to your URL or
what ever pleases. I can add or change any function. Just
let me know. The program is 780k. The link is:
http://www.amasa.com/BPdie.exe

This was one of my most enjoyable projects! It was done
without great expense or special tooling. There are many
ways to build a press with this approach. Maybe this
particular plan will give you some ideas for building
your own.

These first pictures show some of the major component
parts of the press. This is one of two pieces of 4 inch
wide channel. They are 16 inches long and are used at
the top and bottom of the press. They are useful for
mounting eye bolts and the blast shield as well as
providing a space in the base for the large pressure
bearing nuts. I chose to drill the two holes where the
3/4 inch threaded rod goes through. The task of drilling
holes in a piece of channel is not nearly as daunting as
drilling through 3/4 inch flat bar as shown below.

This picture shows one of three pieces of 4 inch wide
flat bar. They are 3/4 inches thick and 14.5 inches
long. A notch has been cut in each end to accommodate a
3/4 inch threaded rod. As you can see, the cutting is
very rough because it was done with a simple cutting
torch by the metal dealer. These three pieces cost me
$15 and the torch cutting cost another $5. You very well
might do better if you try to find this material from a
scrap dealer.

This is the six ton hydraulic piston jack. I purchased
it from an auto parts store for about $20. The force of
this jack is sufficient to bend the pieces of channel.
This is why I needed to use the pieces of flat bar to
reinforce the channel pieces at the top and bottom.

This is a piece of 1.25 inch thick Plexiglas that I used
for the blast shield. I was very fortunate to receive
this free from Donald Haarman who apparently salvaged it
from a dumpster. Thanks again, Donald!! Part of the fun
of these projects is the "scrounge" phase. Whatever is
used for the blast shield, it's very important to
include it. I certainly feel a whole lot safer with 1.25
inches of Plexiglas between the press and my face.

This close-up view of the top shows the channel placed
on top of the flat bar. The threaded rods hold them both
in place with a nut and washer on each side. The blast
shield is bolted to the channel through a wood offset
block. This gives me a little more working room around
the middle pressing deck.

The base of the press is assembled identically to the
top. The retraction springs are attached to eye bolts
which are mounted through the base channel.

This picture shows the attachment of the blast shield to
the base channel. You can also see the bolt which
secures the base of the hydraulic jack to the base of
the press frame.

This view from the opposite side of the blast shield
illustrates the attachment and placement of the
retraction springs. The springs add stability to the
middle pressing deck and conveniently retract it when
the release valve of the jack is opened. These springs
are fairly expensive at $2.85 apiece, but are well worth
the contributions they make to the design.

Finally, the finished product is shown. This press
design was partially inspired by a similar plan sold by
Firefox Enterprises. The major difference is that the
Firefox design places the hydraulic jack on top of the
pressing deck and the object to be pressed is placed on
the base of the pressing frame. This way, the pressing
surface comes down from above, whereas the design shown
here causes the pressing surface to push up. If you are
interested in the Firefox design, it only costs $4.00.

This idea comes to
you from Rich Weaver. I liked it so well, I made the
modifications to my own press. The concept is to add
protective sleeves around the threaded rods to prevent
the press deck from scraping against them as the deck is
raised and lowered. I made the sleeves from 3 inch
lengths of 3/4 inch PVC conduit pipe. I glued a coupler
on one end and then cut the coupler right down the
middle. The PVC tubes had to be notched a little to
allow them to fit into the slots of the press deck.

The sleeves are
installed by using the coupler rings that were cut off
in the step above. The rings are glued and slid over
tubes to lock them into place in the slots of the press
deck as shown. The tubes now act as guides that give the
deck a little more stability and keep it from binding or
scraping against the threaded rods.

I think arc welding the head of the jack right to the
metal plate would help to keep the item(s) being pressed
perpendicular to the plates. -Mike N.

Mike N. suggested arc welding the jack piston directly
to the pressing deck. I suggest arc welding a 4"X4"X1/4"
thick plate to the jack piston in case you ever need to
take the press apart. -Robb W

Robb W. suggested arc welding a 4"X4"X1/4" thick plate
to the jack piston in case you ever need to take the
press apart. I suggest arc welding a large socket to the
4x4x1/4 plate (large enough to accommodate the jack
piston) in case you ever need to replace the jack :)
-Steve K